Apparatus for exposing specimens to maximum amounts of sunlight

ABSTRACT

An apparatus for exposing specimens to sunlight which is always pointed directly at the sun. Electrical circuits are provided which produce an output corresponding to the path of the sun across the sky at the particular location of the apparatus for each successive day of the year so that the specimen holder is always pointed in the direction from which the rays of the sun are coming.

utuwuu l vv--- Inventor Nagaichi Suga No. 2, Tayama-cho, Shinjuku-ku, Takyo, Japan Appl. No. 866,333

Filed Oct. 14, 1969 Patented Jan. 4, 1972 APPARATUS FOR EXPOSING SPECIMENS TO MAXIMUM AMOUNTS OF SUNLIGHT 3 Claims, 8 Drawing Figs.

US. Cl 235/186, 235/151, 318/625 lnt.Cl 606g 7/22, G06! 15/50 Field ofSmrch 235/186,

References Cited l UNITED STATES PATENTS 2,964,645 12/1960 0666mm... 235/186X 3,131,292 4/1964 Tobin,Jr. 235/186X 3,225,279 12/1965 MuldoonetaL. 318/604 3,495,143 2/1970 Deming 318/625 3,513,246 5/1970 Fischetal 235/194 Primary ExaminerMalcolm A. Morrison Assistant Examiner-Jerry Smith Attomey-wenderoth, Lind & Ponack ABSTRACT: An apparatus for exposing specimens to sunlight which is always pointed directly at the sun. Electrical circuits are provided which produce an output corresponding to the path of the sun across the sky at the particular location of the apparatus for each successive day of the year so that the specimen holder is always pointed in the direction from which the rays of the sun are coming.

m D 9 "1 l WENTEBJAH 4m 35331319 SHEET 1 BF 3 INVENTOR NAGAICHI SUGA ATTORNEYS Pmmanm 4:972 alsaaxzna SHEET 2 OF 3 INVENTOR NAGAIC H I SUGA ATTORNEYS TIME WENTEU JAN 4m:

sl gasloia SHEET 3 OF 3 FIGS VERNAL EQUINOX 5 WINTER 8 SOLSTICE 9 0 +90 E S W AZIMUTH ANGLE FIG .8

t SUMMER SOLSTICE LU I O p D 1 VERNAL P EQUINOX S t WINTER F SOLSTICE O L 46 81012141618 TIME F167 INVENTOR NAGAICHI U A BY flax/W55. XXwM ATTORNEYS APPARATUS FOR EXPOSING SPECIMENS T MAXIMUM AMOUNTS OF SUNLIGHT This invention relates to an apparatus for exposing specimens to sunlight and weather. The specimen-carrying means is driven by driving means which is provided with circuits for reproducing the solar orbit and controlling the drive means to drive the specimen-carrying means so that the specimens are exposed to direct sunbeams all the time. The drive means is driven to follow both the sun's azimuth and altitude, so that fading and weathering tests may be carried out rapidly.

In conventional testing methods for fading and weathering, samples are tested by placing then on a frame inclined at an angle of 45 and fixed so as to face to the south.

Because of the frame base is fixed with respect to the position of the sun which is moving over the course of time, such samples are exposed to the sunlight in an inefficient manner, and much time must be spent for exposure before test results can be obtained.

For effective exposure to sunlight during exposure tests, a device which is always directed toward the sun or which can follow the sun, is needed. However there are difficult problems to solve in devising means to follow the sun for any length of time. For example, such mechanical means as are already employed with astronomical telescopes are usually only for following the rotation of the earth, and their ability to follow the sun is limited. Such means will not be very useful for perfect following of the sun because of the necessity for manual adjustment at each time ofobservation or at least once a day.

In a weathering test a device is required which can be operated continuously without any adjustment for at least 1 year. Therefore, such means as described above are not suitable.

Another means which has been used is an electrical means which drives the specimen carrying means to follow the sun by balancing a number of photogalvanic cells or photoelectric tubes greater than two and on which the sun's image or beams are received. However, the operation of such means depends on good weather conditions, and becomes less sensitive with deterioration of such light receptors. For these reasons this means is not satisfactoryv The disadvantages of the prior art devices are eliminated by the apparatus of the present invention, in which a device for carrying out exposure tests is provided which is able to follow the sun for a l year time period on the basis of calculation of the solar orbit.

The invention will be described in greater detail in connection with the accompanying drawings, in which:

FIG. 1 is a diagram showing circuits for calculation of the suns path and control ofthe apparatus;

FIG. 2 is a perspective viewv of a practical mechanism including the circuits of FIG. 1;

FIG. 3 is a perspective view of the exterior of a unit incorporating the mechanism ofFIG. 2',

FIG. 4 is a perspective view of an exposure test device;

FIG. 5 is a diagrammatic view showing movement in the azimuth direction as viewed from above the speciment-carrying frame;

FIG. 6 is a similar view showing movement in the altitude angle viewed from the side of the speciment-carrying frame;

FIG. 7 is a graph showing the relation between seasonal time and the suns altitude; and

FIG. 8 is a graph showing the relation between seasonal time and the azimuth angle.

The altitude and azimuth of the sun at any time is given by formulas; sinh =sinsin 8coscos5cost (I) sinh sindJ-sin 8=cos h cosqScosa (2) where 45: latitude at the point of exposure 8: declination at the time of exposure (for example; 23 in Jan. Tokyo and +22 in June) I Hour angle (0 at the southing, for 1 hour) li at: altitude ofthe sun from a level surface a: azimuth FIGS. 7 and 8 are graphs showing values obtained by calculation based on formulas (l) and (2) of the altitude and azimuth at Tokyo at the vernal equinox, the summer solstice, and the winter solstice.

Control of driving means to cause the apparatus to follow the sun is by a device formed of electric circuits as shown in FIG. 1 and a mechanism using two cams 9 ans l7 as shown in FIG. 2 in combination therewith. Voltage output to satisfy the above formulas l and (2 is balanced to control the altitude and azimuth angle by means of servomotors.

A circuit including voltage detector G, is provided at the upper part of section I in FIG. 1 for calculating the altitude of the sun according to formula l. A circuit including voltage detector G is provided at the upper part of the sectwon 2 for moving the device to the altitude thus calculated. A circuit including voltage detector G at the lower part of section 1 for calculating the azimuth angle according to Formula (2) and a circuit including voltage detector G, is provided at the lower part ofsection 2 for moving the device to the azimuth thus calculated.

R, to R are variable resistances all having stationary elements and movable elements. Eight of the resistances, R, to R, and R to R, are wire wound resistances, which respectively vary as a trigonometric function, the sine or the cosine of the rotary angle of 360 as indicated in the drawing R, R R,, and R, are resistances linear with respect to the rotary angle of360 Resistance R, is equivalent to cos t, R, to 8, R to sinSR, to sinh, R to sinh, and R to sin8, R to cosa, R il, R and R to the altitude h, and R,, and R to the azimuth angle or.

The movable elements of resistances R R and R are fixed on one shaft to be rotated together thereon as indicated by dotted lines, and the movable elements of resistances R, R R and R are mounted on another shaft, also as indicated by dotted lines, and the movable elements of resistances R and R,, are mounted on a third shaft.

Separate DC voltage sources E, to E,,, such as batteries or output from a voltage regulator are connected across the various resistors.

Sources E, E, E,, E, E. and E,,, have the same potential E, and the voltage of source E is multiplied by tan so that, for example, if d =3539', then tand =0.7l725, and voltage E 0.71732E. Source E is voltage E divided by cost!) and sources E and E, are voltage E multiplied by sind) and cosd: respectively.

Voltage detectors G, to G, include servoamplifiers and are coupled to servomotors 20, 39, 18 and 33 respectively.

D is a time axle which is driven by clock or synchronous motor so as to make one station per day and is coupled to the rotary shaft of resistance R,

A cam mechanism S is coupled to the stationary element of resistance R, for moving it slightly for correcting for seasonal changes at the time of culmination (the time when the sun is due south). The range of angles though which cam mechanism S is rotated is about :1 5.

A cam mechanism Y is provided for converting an annual change in the declination of the sun into an angular quantity by turning the rotary shaft connected to resistances R R and R The section 1 enclosed by a chain line in FIG. 1 is structurally embodied as shown in FIG. 2 and is housed in the unit of FIG. 3. In FIG. 1 section 2 servomotors 39 and 33 correspond to servomotors 39 and 33 in FIG. 4. Similarly R and R correspond to resistances 31 and 40 in FIG. 4.

Now the principal of operation will be explained. In the circuit for calculation of altitude of FIG. 1 the voltage E, is divided by resistances R, and R, with the output voltage of resistance R, being E, cos 1 c058. The voltage E is divided in resistance R with the output voltage being E tandzsino. The voltage E is divided in resistance R, with the output voltage being sin h The output voltages from resistances R and r are added, the resistances being connected in series, and thus the poten tial on the left side of voltage detector G, is: E,cos!cos8+ E tantbsinfi. When this potential is balanced with the potential on the right side, the equation E cos it cos 6+E tan sin 6=E sin h cos o is obtained.

By eliminating E from the above equation, as E E E cos (cost cos8+ tansin5) sinh or sink sinsin8+ coscos8cost is obtained. Thus, formula l is satisfied.

Likewise in the circuit for calculation ofazimuth angle with voltages E E and E,,, formula (2) can be satisfied at the voltage detector G Cost is set by continuously rotating the time shaft D of resistance R, at a speed of one rotation per 24 hours with resistances R and R being balanced by the servomotors in voltage detectors G and G and the variation in the time of southing for one a year is corrected by the cam S and declina tion corrected by the cam Y. In this manner the values for altitude and the azimuth from the left side of equations l and (2) are automatically set in resistances R and R respectively through a year through voltage detectors G and G and thence to resistances R and R through the mechanical connections.

Voltages E and E in the control circuit for controlling elevation are divided by resistances R and R respectively and output voltages from resistances R and R are detected by G and resistance R, is balanced to equal resistance R,,. The servomotor 39 coupled to this voltage detector is also usedgs power for the exposure test device (FIG. 4) and operated so as to make the value of an angle calculated and fed to R equal to that of the resistance R A similar arrangement for the azimuth is provided by resistances R and R and servomotor 33.

Referring now to FIG. 2, one mechanical embodiment will be described. One group 4 of variable resistances corresponding to resistances R R and R of FIG. 1, all of which are related to the declination angle 6, are mounted on plate 3 around a shaft 4' with the movable elements on the shaft 4', while resistance 5 which corresponds to resistance R of FIG. I is mounted on plate 3 around shaft 5 with the rotatable element mounted on shaft 5. Shaft 5' corresponds to shaft D of HO. 1. A further group 6 of resistances corresponding to resistances R and R of FIG. 1, all of which are related to the azimuth angle, are mounted on plate 3 around shaft 6 with the movable elements on the shaft 6, while a still further group of 7 of resistances corresponding to resistances R R R and R all of which are related to the altitude angle h, are mounted on plate 3 around a shaft 7 with the movable elements on the shaft 7'. The shaft 5 is driven by a synchronous motor 10 through gearing 10' so as to rotate once each 24 hours, and the gearing 10 is connected to shaft 22 mounted on plate 3 through reduction gearing 11 so as to rotate the shaft 22 once each year. Mounted on shaft 22 are cam 17, corresponding the the cam S ofFIG. I, and cam 9, corresponding to cam Y of FIG. 1. Cam follower and lever systems 16 is coupled between cam 17 and the resistance 5 to rotate the body of resistance 5 slightly in response to the rotation of the cam 17 for correcting for seasonal changes of the time .of southing, and cam follower and lever system 8 is coupled between cam 9 and the shaft 4' to rotate shaft 4' to correct for the annual change in the declination of the sun. Dials l2 and 13 can be provided on shafts 22 and 5** to indicate the hour and the day. Dials l9 and 21 can be provided on the shafts 6' and 7' to indicate the azimuth and elevation. Servomotors I3 and 20, mounted on plate 3, are geared to shafts 6 and 7' respectively for rotating the shafts in response to voltages from the voltage detectors G; and G FIG. 3 shows the external appearance ofa unit in which the mechanism as described above is housed. Servoamplifiers 24 and a voltmeter 23 for checking DC voltage are also provided in the housing.

On the rotary portion of the reduction gears 11 and of the motor 10 there can be provided some sliding means or a clutch for adjustment of data and time by manual control of the dials l2 and 13. If night operation is not required, a time switch or the like may be mounted on the rotary portion of the shaft 5'.

The specimen-carrying part of the apparatus is shown in FIG. 4 and has a box 30 mounted on a base 29, in which a shaft 32 which is rotatable around a vertical axis (for the azimuth), the servomotor 33, and a resistance 31 corresponding to resistance R in FIG. 1 are provided and engaged through gears.

The shaft 32 has fixed on the upper end a box 34, which is rotated horizontally by means of the servomotor 33 by rotation of shaft 32.

On the slanting upper surface of the box 34 is mounted a shaft 35 with frames 37 mounted on the back of a metal or wooden specimen-carrying board 36 mounted on shaft 35 so as to be rotated through the angle corresponding to the altitude of the sun. A balance weight 38 is mounted on one frame 37. A servomotor 39 for the controlling altitude and a resistance 40 for the altitude and corresponding to resistance R in FIG. 1 are mounted in box 34. The shaft 35 is rotated by gears having a suitable reduction ratio. A clutch lever 41 is provided for cutting off or transmitting driving power between the shaft 35 and the motor 40. This is provided in order to permit manual setting of the specimen-carrying board at any desired position so that samples may be easily attached to or detached from the board. The positions of specimens are shown at 42.

FIG. 6 is a side view of the specimen-carrying board, showing the position thereof, where sunbeams are incident thereon as indicated by arrows, and the angle h of inclination shows the altitude ofthe sun.

FIG. 5 is schematic diagram of the specimen-carrying board viewed from above, where a is the azimuth angle, covering at a maximum from the south to the north and to the west respectively.

The present apparatus is very easy to handle and operate. First the specimen-carrying board 36 is moved by hand to position for easy attachment or detachment of samples after actuation of the clutch lever 41 to disconnect the board, and then the clutch is reengaged. The day dial l2 and the time dial 13 are set to the corresponding day and time, and a power switch (not shown) is turned on. The circuit for calculation and control starts to operate so as to cause the device to follow the sun all the times for carrying out exposure tests.

Exposure tests on various kinds of dyed goods using the device of this invention show that they are faded two or three times quicker than those tested on conventional exposure apparatus which is fixed facing to the south.

lclaim:

1. An apparatus for exposing specimens to sunlight, comprising a specimen-holding member; mounting means on which said specimen-holding member is mounted, said mounting means being movable in azimuth and elevation; two driv ing servomotor means coupled to said mounting means, one for driving the mounting means in azimuth and the other for driving the mounting means in elevation; two driving voltage divider means, an azimuth voltage divider means and an elevation voltage divider means, each having a voltage detector therein coupled to the respective driving servomotor, the driving servomotor also being coupled to the respective voltage divider means to balance them in response to a detected voltage difference; an elevation determining circuit having a voltage divider means therein and voltage-resistance means coupled therein for balancing said elevation determining circuit voltage divider means according to the formula sin/t sind) sin8 cosd c055 cost in which d) is the latitude at the point ot'exposure 8 is the declination at the time ofexposure 1 is the hour angle a is the azimuth said elevation determining circuit voltage divider means being coupled to said elevation voltage divider means for unbalancing the elevation voltage divider means in response to the balancing of said elevation determining circuit voltage divider means, and means for varying the voltage-resistance means over a 24-hour time period in accordance with the elevation of the sun; and an azimuth determining circuit having a voltage divider means therein and voltage-resistance means coupled therein for balancing said azimuth determining circuit voltage divider means according to the formula sINh sind sinS cosh c0505 cosa in which it is the altitude of the sun from a level surface and the remaining terms are the same as in the equation for elevation, said azimuth determining circuit voltage divider means being coupled to said azimuth voltage divider means for unbalancing the azimuth driving voltage dipled between said drive motor and said mounting means for enabling drive of said mounting means when said clutch is engaged to set the specimen-holding member in the proper position to start operation of the apparatus. 

1. An apparatus for exposing specimens to sunlight, comprising a specimen-holding member; mounting means on which said specimenholding member is mounted, said mounting means being movable in azimuth and elevation; two driving servomotor means coupled to said mounting means, one for driving the mounting means in azimuth and the other for driving the mounting means in elevation; two driving voltage divider means, an azimuth voltage divider means and an elevation voltage divider means, each having a voltage detector therein coupled to the respective driving servomotor, the driving servomotor also being coupled to the respective voltage divider means to balance them in response to a detected voltage difference; an elevation determining circuit having a voltage divider means therein and voltage-resistance means coupled therein for balancing said elevation determining circuit voltage divider means according to the formula sinh sin phi sin delta + cos phi cos delta cost in which phi is the latitude at the point of exposure delta is the declination at the time of exposure t is the hour angle Alpha is the azimuth said elevation determining circuit voltage divider means being coupled to said elevation voltage divider means for unbalancing the elevation voltage divider means in response to the balancing of said elevation determining circuit voltage divider means, and means for varying the voltage-resistance means over a 24-hour time period in accordance with the elevation of the sun; and an azimuth determining circuit having a voltage divider means therein and voltage-resistance means coupled therein for balancing said azimuth determining circuit voltage divider means according to the formula sinh sin phi - sin delta cosh cos phi cos Alpha in which h is the altitude of the sun from a level surface and the remaining terms are the same as in the equation for elevation, said azimuth determining circuit voltage divider means being coupled to said azimuth voltage divider means for unbalancing the azimuth driving voltage divider means in response to the balancing of said azimuth determining circuit voltage divider means, and means for varying the voltageresistance means over a yearly period according to the change in declination of the sun.
 2. An apparatus as claimed in claim 1 further comprising an elevation correction means is coupled to said elevation determining circuit for feeding a correction to said voltage-resistance means to correct for annual changes in elevation.
 3. An apparatus as claimed in claim 1 further comprising a drive motor for said mounting means aNd clutch means coupled between said drive motor and said mounting means for enabling drive of said mounting means when said clutch is engaged to set the specimen-holding member in the proper position to start operation of the apparatus. 